_Chirp
m
cache
normp
div
cells
poles # list of pole ids
l     # left point on pole i
r     # right point on pole i
a     # a vals for pole i (distance to left)
b     # b vals for pole i (distance to right)
c     # c val for pole i
x     # 
y
lhs    # left most point on pole i
rhs   # right most point on pole i
err   # error
corners # the corners selected so far
sorted # x-items,sorted
xndex 


_Grid
id    # id of the grids
box    # points in the node
axis   #  axis at t 
ats  # a lookup table grid key to node
n      # number of points
s      # sum of class of points
s2     # sum squared
cluster #
owner
descending
neighbor
med
spread


#cluster
 # cell
  #  where
   #   points


